Yes getting closer! My guess is that Glen visited with Michael Parkinson around the time he was touring the UK (April - May 1981). Let's see if we can find a performance from 1980 or very early 1981 with that ending!

Update: I have a recording of Glen performing Rhinestone Cowboy in 1980. Here he ends with a high-pitched "yeah like a rhinestone cowboy!" but during the song he sings "just like them rhinestone cowboys... and girls!" Was that the start of it? I think we assume that somewhere in 1980 or 1981 he started adding "and cowgirls!" at the end of the song.

Hi KMFrye54,
if I may correct you, what I said was that Glen did NOT add "and cowgirls" during his 1977 concert at the Festival Hall in London. He DID add it on his 1981 live album. That 1981 album was recorded on May 8, 1981 at the Cornwall Coliseum, Carlyon Bay, St. Austell, UK. I haven't found the exact date for the Royal Festival Hall concert yet, but usually Glen toured the UK in April, celebrating his birthday there too. I found one reference to Glen playing the Glasgow Apollo on April 15 1977. So I can think we can safely assume The Royal Festival Hall concert was in April/May 1977 (which fits your estimate on the recording date quite well actually). Somewhere between that date and May 8, 1981 Glen started adding "and cowgirls" at the end of Rhinestone Cowboy! I have old tapes of tv and concert appearances from that period so I might be able to pin it down more accurately. And of course we have to find the exact recording date for the Royal Festival Hall concert!

Ok, so to re-cap a little: "Rhinestone Cowboy" came out in May of '75 and by 77 Glen was adding "and Cow gir-r-r-rls" to the end of the song, per the Royal Festival Hall concert.. The issue date of the Live album (November '77) isn't a lot of help, because it really does not equate to the date(s) of the actual show. I did locate a 1978 newspaper reference to "last spring" for a concert date, but even that is pretty vague. Still, let's be kind. Let's give the producers 6 months to pull all the bits together and get the copies in the stores for November. This makes the concert likely some time before May, 1977.

Narrows it down to about a 24 month span at the outside, and more likely less. So all we need is some first-hand evidence from a concert attendee (or even a bootleg tape) between May of 75 and May of 77 to see if he used the extra line or if it was literally "new" for the album.

What's interesting to me, is that those "enhancements" (imho) are remembered by his serious fans. Guitar solos, and cowgirlllllllllllllllll, and I'm doing fiiiiiiiiiiiiiiiiiiiiiiiiiinnnnnnnnnnnnnnneeeeeeeeeeee, or the galveston closing, such as In good ole Branson , Missouuuuurrrriiiiiiiiii, are remembered mostly by his most serious fans, and not so much by his casual fans. And of course I realize, those "enhancements" are fun things that were not needed on his hits when originally recorded, yet got a very noticeable positive reaction later from his serious fans when he started adding them in.

Ha you made me go and listen to some more concert recordings. Turns out Glen already did it on his 1981 Glen Campbell Live album, recorded in England. On Live at the Royal Festival Hall from 1977 he justs ends with ‘like a rhinestone cowboy”. So we have pinned it down to somewhere between 1977 and 1981! I wonder if we can get it even more accurate.